1. Field of the Invention
The present invention relates to a durable piston and its ring unit, and more particularly to a piston being applied in an internal combustion engine to output internal exploding power.
2. Description of the Prior Arts
With reference to FIG. 10, a conventional piston (50) is applied in an internal combustion engine to output internal exploding power generated by burning fuel such as gas, diesel, petrol, ethanol or the like in a cylinder (60) of the engine.
The piston (50) is mounted slidably in the cylinder (60), is adjacent to a fuel chamber (61) of the cylinder (60), is driven to output kinetic energy when the fuel is burned in the fuel chamber (61) and has an annular wall, multiple annular grooves (51, 52) and multiple piston rings (54, 55).
The annular wall of the piston (50) corresponds to an inner wall of the cylinder (60).
The annular grooves (51, 52) are formed around the annular wall of the piston (50).
The piston rings (54, 55) are respectively mounted in the annular grooves (51, 52) and abut the inner wall of the cylinder (60) to seal the fuel chamber (61) and prevent air in the fuel chamber (61) from leaking.
However, after operating for a long time, friction generated between the piston rings (54, 55) and the inner wall of the cylinder (60) wears the piston rings (54, 55) or the inner wall of the cylinder (60) and cause leakage of air from the fuel chamber (61), which prevents complete combustion in the fuel chamber (61). Incomplete combustion not only decreases outputted power of the engine, but also pollutes the environment.
To overcome the shortcomings, the present invention provides a durable piston to mitigate or obviate the aforementioned problems.